Iris scan technology offers great promise to dramatically improve user authentication and security. Generally speaking, user authentication techniques can be organized under three categories: what the user knows (e.g., password), what the user has (e.g., smart card or fob), and what the user is—i.e., biometric authentication. Of these, biometric authentication is considered to be superior, because it can provide more protection against spoofing and loss. A password can be copied, as well as lost if a user forgets his/her password. A smart card or fob can be physically misplaced. A biometric characteristic is more difficult to spoof and unlikely to be misplaced by the user. A biometric authentication technique, used either alone or in combination with one or more other authentication techniques, provides a markedly greater level of security. Among biometric authentication techniques, iris scan technology is particularly interesting in terms of the level of protection it can potentially provide. Currently, fingerprint matching is the most widely adopted form of biometric authentication. However, the uniqueness of a human fingerprint is estimated to be on order of one (1) in ten thousand (10,000) or one hundred thousand (100,000). By contrast, the uniqueness of a single human iris scan is estimated to be on order of one (1) in one million (1,000,000). Furthermore, iris scans can usually be taken for both the left eye and the right eye of a user simultaneously, which effectively results in the uniqueness of the scan (of both eyes) being estimated to be on order of one (1) in one trillion (1,000,000,000,000). Iris scan technology can thus provide a dramatic improvement over traditional biometric authentication based on fingerprint matching.
However, iris scan technology has not been widely used for user authentication. One significant reason relates to power consumption. An iris scan involves capturing an image of the user's iris with sufficient level of detail to include iris features. Furthermore, the process of matching a captured iris image to a registered iris image generally involves a considerable level of processing capability. The amount of power required to perform such tasks can be significant, especially for battery-powered devices such as mobile devices, wearable devices, etc. Exacerbating the problem is the need to keep power-hungry systems, such as camera and processor systems, in a powered-on state in anticipation of the occurrence of an iris scan. Consequently, even though it has tremendous potential, iris scan technology continues to be limited in its adoption.